The present invention includes a method for analyzing an image to screen for target candidates wherein an edge-follower detects straight segments within a plurality of longer edges and detects also from the longer edges, contours that go around areas that are the right size. A lens may have a lens surface that reflects the test pattern of light. The data from at least one sensor is analyzed in order to detect events occurring in proximity to the sensor. Testing is executed in two steps, making the threshold shifting circuit active when a first voltage is applied across test inputs and comparing a second voltage at the test input with the shifted threshold. The second hydraulic circuit includes a bypass valve. The wind deflector is movable by means of the operating element between a raised position and a lowered position.